Over the road trailer-tractors are a major single factor in our industrial economy and they contribute to the prompt and economical transport of goods throughout this nation. The separatable element (usually a multi-wheeled entity) undergoes many hauls that is sometimes switched from tractor to tractor. Efficient and durable fabrication of trailers is a major construction industry. A means to permit fabrication of trailer sidewalls of variable length and durability is an important business goal. There is an existing industry for the building of trailers from rigid-metallic panels, or modules, having standardized dimensions. While the abutting panel heights may be commonly matched, the sidewall lengths depend upon the number of modules arrayed, and interlocked, and needed to produce a given length of a trailer sidewall.
Interlocking, along lateral vertical edges, of the modules is a feature crucial to present smooth, sidewall products. Smooth sidewalls reduce air drag and improve road mileage of tractor-trailers. Fabricating sidewall modules is a chore of continuing concern, to combine reasonable cost, to foster efficient assembly of the abutting panels, and to provide for long-term sidewall durability, given the over-the-road physical stressors that burden trailer longevity.